Acer rubrum

red maple

Did you know?:

This is one of the species in our North American forests that provides brilliant autumn coloring. The sap from this plant is suitable for syrup production, though the tapping season is shorter than sugar maple because of its earlier flowering.

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What does this species look like?

Red maple is a deciduous tree growing 30 to 90 feet tall. Its tiny, usually red, male and female flowers mostly occur separately on the same tree but occasionally can occur on different trees.

Red maple is often found in swamps and on moist soils, but can also thrive in drier habitats. It occurs on moist soils along stream banks, and in swamps, moist to drier woodlands, and occasionally on dry rocky hillsides and sand dunes. It is moderately shade-tolerant.

Why observe this species?

Red maple is a USA-NPN calibration plant species. Calibration species have broad distributions and are ecologically or economically important. The NPN integrates observations on calibration species to get "the big picture" of plant responses to climate across the nation. In addition, this species is an allergen. Observations on its phenology will provide valuable information to benefit people with allergies and the public health community.

Where is this species found?

U.S. States:

AL, AR, CT, DC, DE, FL, GA, IA, IL, IN, KY, LA, MA, MD, ME, MI, MN, MO, MS, NC, NH, NJ, NY, OH, OK, PA, RI, SC, TN, TX, VA, VT, WI, WV

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Special Considerations for Observing

If drought seems to be the cause of leaf color or fall for a plant, please make a comment about it for that observation.

This species has separate male and female flowers. If you know whether the flowers you are observing are male or female (or both), please make a comment about it for that observation.

Note that individuals of this species with only male flowers will not produce fruit.

Which phenophases should I observe?

Leaves	Do you see...? *Breaking leaf buds* One or more breaking leaf buds are visible on the plant. A leaf bud is considered "breaking" once a green leaf tip is visible at the end of the bud, but before the first leaf from the bud has unfolded to expose the leaf stalk (petiole) or leaf base. For Acer rubrum, leaf tips may appear reddish. How many buds are breaking? Less than 3 3 to 10 11 to 100 101 to 1,000 1,001 to 10,000 More than 10,000 More... *Leaves* One or more live, unfolded leaves are visible on the plant. A leaf is considered "unfolded" once its entire length has emerged from the breaking bud so that the leaf stalk (petiole) or leaf base is visible at its point of attachment to the stem. Do not include fully dried or dead leaves. What percentage of the canopy is full with leaves? Ignore dead branches in your estimate. Less than 5% 5-24% 25-49% 50-74% 75-94% 95% or more More... *Increasing leaf size* A majority of leaves on the plant have not yet reached their full size and are still growing larger. Do not include new leaves that continue to emerge at the ends of elongating stems throughout the growing season. What percentage of full size are most leaves? Less than 25% 25-49% 50-74% 75-94% 95% or more More... *Colored leaves* One or more leaves (including any that have recently fallen from the plant) have turned to their late-season colors. Do not include fully dried or dead leaves that remain on the plant. What percentage of the canopy is full with colored leaves? Less than 5% 5-24% 25-49% 50-74% 75-94% 95% or more More... *Falling leaves* One or more leaves are falling or have recently fallen from the plant. More...
Flowers	Do you see...? *Flowers or flower buds* One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds that are still developing, but do not include wilted or dried flowers. How many flowers and flower buds are present? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), simply estimate the number of flower heads, spikes or catkins and not the number of individual flowers. Less than 3 3 to 10 11 to 100 101 to 1,000 1,001 to 10,000 More than 10,000 More... *Open flowers* One or more open, fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between or within unfolded or open flower parts (petals, floral tubes or sepals). Do not include wilted or dried flowers. What percentage of all fresh flowers (buds plus unopened plus open) on the plant are open? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), estimate the percentage of all individual flowers that are open. Less than 5% 5-24% 25-49% 50-74% 75-94% 95% or more More... *Pollen release* One or more flowers on the plant release visible pollen grains when gently shaken or blown into your palm or onto a dark surface. How much pollen is released? Little: Only a few grains are released. Some: Many grains are released. Lots: A layer of pollen covers your palm, or a cloud of pollen can be seen in the air when the wind blows More...
Fruits	Do you see...? *Fruits* One or more fruits are visible on the plant. For Acer rubrum, the fruit is two joined seeds in a "V" shape, each seed having a wing, that changes from green or red to tan or brownish and drops from the plant. How many fruits are present? Less than 3 3 to 10 11 to 100 101 to 1,000 1,001 to 10,000 More than 10,000 More... *Ripe fruits* One or more ripe fruits are visible on the plant. For Acer rubrum, a fruit is considered ripe when it has turned tan or brownish and readily drops from the plant when touched. What percentage of all fruits (unripe plus ripe) on the plant are ripe? Less than 5% 5-24% 25-49% 50-74% 75-94% 95% or more More... *Recent fruit or seed drop* One or more mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind, or empty fruits that had long ago dropped all of their seeds but remained on the plant. How many mature fruits have dropped seeds or have completely dropped or been removed from the plant since your last visit? Less than 3 3 to 10 11 to 100 101 to 1,000 1,001 to 10,000 More than 10,000 More...

Leaves

Do you see...?

Breaking leaf buds
One or more breaking leaf buds are visible on the plant. A leaf bud is considered "breaking" once a green leaf tip is visible at the end of the bud, but before the first leaf from the bud has unfolded to expose the leaf stalk (petiole) or leaf base. For Acer rubrum, leaf tips may appear reddish.

How many buds are breaking?

Less than 3

3 to 10

11 to 100

101 to 1,000

1,001 to 10,000

More than 10,000

More...

Leaves
One or more live, unfolded leaves are visible on the plant. A leaf is considered "unfolded" once its entire length has emerged from the breaking bud so that the leaf stalk (petiole) or leaf base is visible at its point of attachment to the stem. Do not include fully dried or dead leaves.

What percentage of the canopy is full with leaves? Ignore dead branches in your estimate.

Less than 5%

5-24%

25-49%

50-74%

75-94%

95% or more

More...

Increasing leaf size
A majority of leaves on the plant have not yet reached their full size and are still growing larger. Do not include new leaves that continue to emerge at the ends of elongating stems throughout the growing season.

What percentage of full size are most leaves?

Less than 25%

25-49%

50-74%

75-94%

95% or more

More...

Colored leaves
One or more leaves (including any that have recently fallen from the plant) have turned to their late-season colors. Do not include fully dried or dead leaves that remain on the plant.

What percentage of the canopy is full with colored leaves?

Less than 5%

5-24%

25-49%

50-74%

75-94%

95% or more

More...

Falling leaves
One or more leaves are falling or have recently fallen from the plant. More...

Flowers

Do you see...?

Flowers or flower buds
One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds that are still developing, but do not include wilted or dried flowers.

How many flowers and flower buds are present? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), simply estimate the number of flower heads, spikes or catkins and not the number of individual flowers.

Less than 3

3 to 10

11 to 100

101 to 1,000

1,001 to 10,000

More than 10,000

More...

Open flowers
One or more open, fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between or within unfolded or open flower parts (petals, floral tubes or sepals). Do not include wilted or dried flowers.

What percentage of all fresh flowers (buds plus unopened plus open) on the plant are open? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), estimate the percentage of all individual flowers that are open.

Less than 5%

5-24%

25-49%

50-74%

75-94%

95% or more

More...

Pollen release
One or more flowers on the plant release visible pollen grains when gently shaken or blown into your palm or onto a dark surface.

How much pollen is released?

Little: Only a few grains are released.

Some: Many grains are released.

Lots: A layer of pollen covers your palm, or a cloud of pollen can be seen in the air when the wind blows

More...

Fruits

Do you see...?

Fruits
One or more fruits are visible on the plant. For Acer rubrum, the fruit is two joined seeds in a "V" shape, each seed having a wing, that changes from green or red to tan or brownish and drops from the plant.

How many fruits are present?

Less than 3

3 to 10

11 to 100

101 to 1,000

1,001 to 10,000

More than 10,000

More...

Ripe fruits
One or more ripe fruits are visible on the plant. For Acer rubrum, a fruit is considered ripe when it has turned tan or brownish and readily drops from the plant when touched.

What percentage of all fruits (unripe plus ripe) on the plant are ripe?

Less than 5%

5-24%

25-49%

50-74%

75-94%

95% or more

More...

Recent fruit or seed drop
One or more mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind, or empty fruits that had long ago dropped all of their seeds but remained on the plant.

How many mature fruits have dropped seeds or have completely dropped or been removed from the plant since your last visit?

Less than 3

3 to 10

11 to 100

101 to 1,000

1,001 to 10,000

More than 10,000

More...

For more information

USDA PLANTS profile for red maple (USDA Symbol: ACRU)
ITIS information for red maple (ITIS TSN: 28728)

Acknowledgments

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